Disposable safety syringe

ABSTRACT

Disclosed is a syringe assembly which greatly reduces the chances of an operator coming in contact with an infectious needle. The syringe assembly is initially provided with its needle retracted within its barrel, in a sterile and safe environment. When used, the needle is engaged by the plunger, and locked in place at the forward end of the syringe barrel. Before disposal, the needle is withdrawn back into the barrel, and the plunger is broken off. Thus, the disposed of syringe is incapable of being reused, and there is little or no danger of accidental punctures, because the needle is retained within the syringe barrel.

FIELD OF THE INVENTION

This invention relates to a disposable syringe which initially isprovided with its needle retracted within its barrel, in a sterile andsafe environment. When used, the needle is engaged by the plunger, andlocked in place at the forward end of the syringe. Before disposal, theneedle is withdrawn back into the barrel, and the plunger is broken off.Thus, the disposed of syringe is incapable of being reused, and there islittle or no danger of accidental punctures, because the needle isretained within the syringe barrel.

BACKGROUND OF THE INVENTION

The concern over protecting medical personnel from coming into contactwith infectious diseases by contact with contaminated syringe needleshas led to the development of many syringes with retractable needles.The recent concern over the avoidance of being infected with the HIV (orAIDS) virus has led to even a greater importance being placed in the useof syringes incorporating retractable needles.

U.S. Pat. Nos. 4,650,468 and 4,643,199 are examples of syringes whichhave been developed so as to allow for a potentially infectious needleto be withdrawn into the syringe's interior after use. Both of thesespatents utilize a somewhat complex mechanism to position the needle inan operational position and/or to retract the needle back into thesyringe housing. The complexity of these designs can be a problem whenquick positioning of the needle is essential, e.g., in an emergencysituation.

U.S. Pat. Nos. 4,507,117 and 4,675,005 illustrate other syringe designshaving retractable needles which are releasably connected directly tothe plunger by way of rotation. As above, the complex mechanismsemployed by these syringe designs can be a problem when quickpositioning of the needle is essential, e.g., in an emergency situation.

U.S. Pat. No. 4,692,156 shows a retractable syringe needle which islocked directly onto the sealing plug of a plunger. In one embodiment,there is disclosed a snapping connection means between the needle andplug. Once this snapping connection has been made, it is essentiallynondetachable and thus this invention represents a one shot device. Inother words, any inadvertent attachment before use cannot be remedied.

Other syringes having safety features that have been designed to preventaccidental punctures and/or which prevent reuse are shown in thefollowing patents:

U.S. Pat. No. 4,664,653 which describes a one step manually activatedinjection apparatus capable of injecting multiple premeasured dose ofliquid medicaments without visibility of the needle.

U.S. Pat. No. 3,677,245 which discloses a self-contained disposablesyringe including a syringe barrel with an open rear end and a needlemounted on the forward end. The needle has a passage therethrough whichcommunicates with the interior of the barrel. A plunger is positionedwithin the syringe barrel and is movable with respect to the barrel.

U.S. Pat. No. 2,888,923 which describes a syringe for use with a sterileneedle comprising a casing and a piston slidably engaged with saidcasing. The piston comprises a first hollow tube and a second hollowtube within and threadably engaging the first hollow tube. The secondhollow tube is axially adjustable with respect to the first hollow tubeand adapted for substantially complete insertion therein, whereby thepiston length maybe controlled.

U.S. Pat. No. 3,584,626 which discloses a hypodermic syringe having asyringe body, a piston rod arranged movably in the body and an injectionneedle, in which the injection needle is housed inside the syringe bodyprior to the use of the syringe. When the needle is moved into itsinjection position, it is brought into a sealing abutment with a seatingmember arranged in the syringe body.

U.S. Pat. No. 4,316,463 which discloses a hypodermic injection devicewherein the needle is initially isolated from a possibly corrosivemedicament, but wherein the needle is movable to a position in flowcommunication with the medicament only at the moment of injection.

U.S. Pat. No. 4,969,877 discloses a syringe assembly which includes anouter casing within which an inner chamber slides. A plunger having asealing plug at one end extends into both the inner chamber and outercasing such that the sealing plug is fixedly secured within the interiorof the inner chamber and outer casing, yet is free to slide along thelength of the inner chamber. The inner chamber and outer casings arestructured such that the needle can be retracted completely within theinterior of the outer casing when the inner chamber is releasably lockedat the rear end of the outer casing. The needle can also be placed intoan operational position when the inner chamber with attached needle isreleasably locked at the forefront of the outer casing.

U.S. Pat. No. 4,915,699 describes a syringe assembly which includes anouter casing within which an inner chamber slides. A plunger having asealing plug at one end extends into both the inner chamber and outercasing such that the sealing plug is fixedly secured within the interiorof the inner chamber and outer casing, yet free to slide along thelength of the inner chamber. The inner chamber and outer casing arestructured such that the needle can be retracted completely within theinterior of the outer casing when the inner chamber is releasably lockedat the rear end of the outer casing.

SUMMARY OF THE INVENTION

The present invention provides a disposable hypodermic syringe whereinthe needle is initially provided in a sterile and protected position,and where after an injection is given, the needle is again easilyreturned to the protective position for safe disposal.

One principal object of the present invention was to provide a simpledesign, having few moving parts, so that the syringe could be readilymanufactured from inexpensive, but FDA acceptable materials that, due totheir low cost, are deemed disposable, e.g., injection molded plastics.Another object of the present invention was to design a disposablesyringe that would be useful as required, but which after use, would benearly impossible to reuse, i.e., a one-time-only syringe.

These and other objects of the invention have been accomplished bydesigning the present syringe which consists of five simple components;(1) an injection molded syringe barrel with a constricted neck portion;(2) an injection molded plunger assembly, with (3) a rubber gasketlocated near the front end thereof (used to form the necessary vacuum)and the male locking portion of a 1/4-turn "T" turn mechanism situatedat its forward end; a needle assembly, consisting of (4) an injectionmolded hub including a 1/4-turn "T" receptacle (i.e., female end) moldedin place at the rearward end, and (5) a conventional syringe needlebonded to the forward end of the hub.

As sold, the syringe will have the needle assembly withdrawn into thebarrel, with the plunger assembly either engaged or disengaged, (butpreferably engaged). Advantageously, the forward tip of the syringe willinclude a thin segment of plastic or other sealing material so that theinterior of the syringe can remain sterile until use.

To use the syringe of the present invention, the plunger assembly isinserted into the rear end of the needle assembly and this combinationis pushed forward. The needle pierces the sealing material at the end ofthe barrel, and the forward tip of the needle assembly fits snugly andsecurely within the tip of the barrel. The two tip members are designedto provide a frictional interference or wedge fit which will withstandthe force typically used during the injection process, but which, with aslight twisting motion on the plunger, can be disengaged when thesyringe is to be disposed of.

Once the tips are locked, the syringe is filled with the injectablematerial by pulling back the plunger assembly an appropriate amount. Theinjection is made by inserting the needle as appropriate, and theplunger is depressed, injecting the contents. The plunger assembly isthen used to reengage the needle assembly, using the 1/4-turn "T"locking means, and the needle assembly locked on and then pulled backinto the safety position, i.e., back into the syringe barrel.Advantageously, a score line is provided at the forward end of theplunger, and this score line becomes visible only after the needle hasbeen fully retracted into the syringe barrel. Once the score line hasbeen exposed, the plunger is snapped off, rendering the syringeincapable of reuse. The needle is safely housed within the barrel andthe two pieces may be disposed of as required by law.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut away view of the syringe of the presentinvention, illustrating the needle in its "on-sale" mode, i.e., in asterile condition.

FIG. 2 is a partially cut away view of the syringe of the presentinvention, showing the positioning of the needle assembly and plungerwhen ready for use (or immediately after use).

FIG. 3 is a partially cut away view of the syringe of the presentinvention, showing the detachment of the plunger assembly, e.g., forfilling of the syringe with an injectable material.

FIG. 4 is a partially cut away view of the syringe of the presentinvention, showing the positioning of the plunger assembly when aninjection is being given (or has been given).

FIG. 5 is a partially cut away view of the syringe of the presentinvention, showing the positioning of the plunger assembly and theneedle assembly after use, with the plunger assembly being broken off atthe score line.

FIG. 6 is a close up view of the disconnected male and female portionsof the 1/4-turn "T" locking mechanisms on the plunger and needleassemblies respectively.

FIG. 7 is a sectional view of the connected male and female portions ofthe 1/4-turn "T" locking mechanisms on the plunger and needleassemblies, as well as the matched tip members of the barrel and needleassembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring in detail to the drawings accompanying this disclosure, thepresent invention is directed to a disposable safety syringe. Asillustrated in FIG. 1, the syringe of the present invention consists ofan injection molded plastic barrel 10, which includes a tip portion 12,which, prior to use, is safety sealed at the end of the tip 13. Thebarrel is advantageously molded to include finger grips 14 at the backend.

As further illustrated in FIG. 1, the syringe of the present inventionincludes an injection molded plunger member 16, which includes a thumbpad 17 at its back end, and includes a separate rubber gasket 18 nearits forward end. The rubber gasket 18 creates the necessary seal betweenthe forward end of the plunger and the barrel of the syringe, so thatthe syringe will operate in a conventional manner. Finally, asillustrated, the plunger body 16 is provided with a score line 19, whichallows the plunger to be easily broken off after use, rendering thesyringe incapable of reuse.

Finally, as shown in FIG. 1, the syringe of the present inventionincludes a needle assembly consisting of an injection molded hub 20which includes a tip member 21 and which terminates with a needle 22 atits forward end. The rear portion of hub 20 consists of a 1/4-turn "T"receptacle, adapted to accept a corresponding male 1/4-turn "T" memberon the forward end of the plunger 16. These features will be moreapparent in the later figure descriptions.

As illustrated in FIG. 1, the very tip of the barrel 13 is injectionmolded to be closed by a thin plastic membrane, so that the needle canbe kept in a sterile position. By pushing the plunger and the needleforward, the needle 22 will push through the plastic membrane 13, andthe tip 21 of the needle assembly 20 will fit snugly within tip 12 ofthe syringe barrel. Plastic tip membrane 13 is advantageously made via aflash area in the mold so the wall of the membrane will have abreakthrough point to allow the needle to pass easily through it. Asillustrated in FIG. 2, this allows the needle to come forward in itsposition to be useful for giving an injection.

As shown in FIG. 2, needle 22 has been pushed through tip 13, and now islocated outside the syringe barrel 10, in a ready to use position. Bycareful design, the tip of the syringe barrel 12 and the tip of theneedle assembly 21, have been matched in size to create a wedge fitbetween the two components.

The wedge fit between tips 12 and 21 is one of the necessary componentsthat establish the tight fit for the syringe of the present invention toform a simple vacuum seal. The other vacuum seal component is rubbergasket 18, located near the forward end of plunger 16. Gasket 18 isdesigned to have a tight tolerance between the inside wall of thesyringe barrel, and this tight, but flexible fit, allows the plunger tobe easily moved back and forth inside the barrel, thereby enabling thesyringe to draw and/or discharge liquids. The gasket is advantageouslymade of a soft synthetic rubberized material that is FDA approved.

FIG. 3 illustrates the typical positioning of the plunger assembly inthe syringe after filling with an injectable solution (not shown). Thevacuum seal created by gasket 18 and tips 12 and 21, allows the syringeto be filled with an injectable solution (not shown) as the plunger 16is pulled back.

FIG. 4 illustrates the typical positioning of the plunger assembly asthe contents of the syringe are being (or have been ) injected. Asillustrated, gasket 18 on the plunger assembly is preferably shaped in aconfiguration that creates a wiper effect in the barrel of the syringe,i.e., as it's drawn or pushed inside the barrel, thus maintaining an airtight seal, and ensuring both secure filling of the syringe, and asshown in FIG. 4, complete delivery of the syringe contents.

As illustrated in FIG. 5, after the syringe has been used to give aninjection, the needle assembly is drawn back into the syringe barrel.This is accomplished by mating the male and female 1/4-turn "T" memberson the front end of the plunger assembly and on the back end of theneedle assembly. For a close-up view of these assemblies, see FIG. 6.Once the needle assembly has been returned to the safe position withinthe syringe barrel, the plunger is withdrawn enough to expose score line19. Once the score line on the plunger has been exposed at the back ofthe syringe, the plunger arm may be simply broken off. Advantageously,the score line is created during the molding of the plunger assembly,but it may be created by any means available to the skilled artisan.

FIG. 7 illustrates in cross-section, the wedge fit between tips 12 and21 which assures that needle 22 will be held securely in a rigid stateduring both the filling of the syringe, as well (and most importantly)during the injection of the syringe contents into a patient. The wedgefit is sufficient to prevent the needle from being pushed back duringuse, but with a simple twist and pulling of the plunger, the needle maybe retracted into the syringe barrel for safe disposal.

The components of the syringe of the present invention can bemanufactured using any available material that meets the criteria of theinvention. For commercial purposes, the manufacturing materials shouldbe FDA approved. In other words, while injection molded plastics havebeen touted herein as a most convenient material for the syringecomponents, other commonly used syringe components can be adapted tobenefit from the teachings of the present invention.

It will also be apparent to those having ordinary skill in this field,that any size syringe can be prepared according to the teachings of thepresent invention. Similarly, while the 1/4-turn "T" type lockingmechanism has been described herein as being convenient and simple,those artisans having ordinary skill in this field will recognize thatother simple locking means can be employed herein, so long as theyfunction in a manner consistent with the teachings of this invention.

While the present invention has been described in conjunction with thepreferred specific embodiments thereof, it will be understood that thedescription is intended to illustrate and not limit the scope of theinvention which is defined by the following claims.

What is claimed is:
 1. A disposable safety syringe assemblycomprising:(a) a substantially elongated barrel assembly, said barrelassembly having a forward end, a rearward end, an exterior surface andan Interior surface, with the interior surface defining an interiorspace, and wherein the barrel assembly is open ended in its rearwardend, and wherein the forward end is provided with a constricted neckportion having a bore extending at least partially therethrough, and aneedle breakable seal at the end thereof; (b) a backward and forwardslidable needle assembly, disposed within said barrel assembly, saidneedle assembly including a substantially cylindrical hub member havinga forward end and a rearward end, wherein the rearward end is providedwith a locking member, and the forward end is provided with aconstricted neck portion, said hub member further having a boretherethrough for communicating with the interior space of the barrelassembly; andwherein said constricted neck portion of said needleassembly is of a size and shape to removably wedge fit within theconstricted neck portion of said barrel assembly, and wherein saidneedle assembly further includes a hollow needle mounted within theforward end of said hub member and passing through said constricted neckportion; and (c) a plunger assembly including a rod portion movable withrespect to the syringe barrel assembly, said rod portion including agasket member mounted on the rod near its forward end, and terminatingwith a locking member at its forward end, said locking member beingcapable of locking and unlocking with the locking member of the needleassembly; (d) wherein said locking member on said needle assemblyconsists of the female half of a 1/4-turn "T" mechanism.
 2. Thedisposable safety syringe assembly of claim 1, wherein said gasketmember on said plunger assembly comprises a resilient material capableof engaging in a sealing frictional engagement with the inner wall ofthe syringe barrel assembly, and wherein said resilient material isslidable with respect thereto, thereby facilitating the drawing ofliquid into said barrel upon retraction of said plunger and projectionof said fluid from said barrel upon protraction of said plunger.
 3. Adisposable safety syringe assembly comprising:(a) a substantiallyelongated barrel assembly, said barrel assembly having a forward end, arearward end, an exterior surface and an Interior surface, with theinterior surface defining an interior space, and wherein the barrelassembly is open ended in its rearward end, and wherein the forward endis provided with a constricted neck portion having a bore extending atleast partially therethrough, and a needle breakable seal at the endthereof; (b) a backward and forward slidable needle assembly, disposedwithin said barrel assembly, said needle assembly including asubstantially cylindrical hub member having a forward end and a rearwardend, wherein the rearward end is provided with a locking member, and theforward end is provided with a constricted neck portion, said hub memberfurther having a bore therethrough for communicating with the interiorspace of the barrel assembly; andwherein said constricted neck portionof said needle assembly is of a size and shape to removably wedge fitwithin the constricted neck portion of said barrel assembly, and whereinsaid needle assembly further includes a hollow needle mounted within theforward end of said hub member and passing through said constricted neckportion; and (c) a plunger assembly including a rod portion movable withrespect to the syringe barrel assembly, said rod portion including agasket member mounted on the rod near its forward end, and terminatingwith a locking member at its forward end, said locking member beingcapable of locking and unlocking with the locking member of the needleassembly; (d) wherein said locking member on said plunger assemblyconsists of the male half of a 1/4-turn "T" mechanism.
 4. The disposablesafety syringe assembly of claim 1 or 3, wherein the locking members onsaid needle and plunger assemblies are adapted for repeated movement oflocking and unlocking and when locked are capable of drawing said needleback into the syringe barrel assembly.
 5. The disposable safety syringeassembly of claim 1 or 3, in which the syringe assembly is sealed in asterile manner.
 6. The disposable safety syringe assembly of claim 1 or3, wherein the needle assembly has been pushed through the forward endof the barrel assembly, and locked therein by the friction between thetwo constricted tip portions, forming an interference or wedge fit. 7.The disposable safety syringe assembly of claim 1 or 3, wherein thebarrel assembly includes a finger extension extending radially outward,said finger extension being positioned closer to said rearward end thanto said forward end thereof.
 8. The disposable safety syringe assemblyof claim 1 or 3, wherein the plunger assembly includes a break-offmeans, located closer to said forward end than to said rearward endthereof, such that after withdrawal of the needle assembly into saidbarrel assembly, said plunger assembly may be broken off, rendering thesyringe incapable of reuse.
 9. The disposable safety syringe assembly ofclaim 8, wherein the plunger assembly has been broken off via thebreak-off means, and whereby the needle assembly is retained within thebarrel assembly, such that the syringe is suitable for disposal.
 10. Adisposable safety syringe assembly consisting of:(a) a substantiallyelongated barrel assembly, said barrel assembly having a forward end, arearward end, an exterior surface and an interior surface, with theinterior surface defining an interior space, and wherein the barrelassembly is open ended in its rearward end, and wherein is open ended inits rearward end, and wherein the forward end is provided with aconstricted neck portion having a bore extending at least partiallytherethrough, and a needle breakable seal at the end thereof; (b) abackward and forward slidable needle assembly, disposed within saidbarrel assembly, said needle assembly including a substantiallycylindrical hub member having a forward end and a rearward end, whereinthe rearward end is provided with a locking member, and the forward endis provided with a constricted neck portion, said hub member furtherhaving a bore therethrough for communicating with the interior space ofthe barrel assembly;wherein said constricted neck portion of said needleassembly is of a size and shape to removably wedge fit within theconstricted neck portion of said barrel assembly, and wherein saidneedle assembly further includes a hollow needle mounted within theforward end of said hub member and passing through said constricted neckportion; and (c) a plunger assembly including a rod portion movable withrespect to the syringe barrel assembly, said rod portion including agasket member mounted on the rod near its forward end, and terminatingwith a locking member at its forward end, said locking member beingcapable of locking and unlocking with the locking member of the needleassembly; (d) wherein said locking member on said needle assemblyconsists of the female half of a 1/4-turn "T" mechanism.
 11. Adisposable safety syringe assembly consisting of:(a) a substantiallyelongated barrel assembly, said barrel assembly having a forward end, arearward end, an exterior surface and an interior surface, with theinterior surface defining an interior space, and wherein the barrelassembly is open ended in its rearward end, and wherein the forward endis provided with a constricted neck portion having a bore extending atleast partially therethrough, and a needle breakable seal at the endthereof; (b) a backward and forward slidable needle assembly, disposedwithin said barrel assembly, said needle assembly including asubstantially cylindrical hub member having a forward end and a rearwardend, wherein the rearward end is provided with a locking member, and theforward end is provided with a constricted neck portion, said hub memberfurther having a bore therethrough for communicating with the interiorspace of the barrel assembly;wherein said constricted neck portion ofsaid needle assembly is of a size and shape to removable wedge fitwithin the constricted neck portion of said barrel assembly, and whereinsaid needle assembly further includes a hollow needle mounted within theforward end of said hub member and passing through said constricted neckportion; and (c) a plunger assembly including a rod portion movable withrespect to the syringe barrel assembly, said rod portion including agasket member mounted on the rod near its forward end, and terminatingwith a locking member at its forward end, said locking member beingcapable of locking and unlocking with the locking member of the needleassembly; (d) wherein said locking member on said plunger assemblyconsists of the male half of a 1/4-turn "T" mechanism.
 12. Thedisposable safety syringe assembly of claim 10 or 11, wherein saidgasket member on said plunger assembly consists of a resilient materialcapable of engaging in a sealing frictional engagement with the innerwall of the syringe barrel assembly, and wherein said resilient materialis slidable with respect thereto, thereby facilitating the drawing ofliquid into said barrel upon retraction of said plunger and projectionof said fluid from said barrel upon protraction of said plunger.
 13. Thedisposable safety syringe assembly of claim 10 or 11, wherein thelocking members on said needle and plunger assemblies are adapted forrepeated movement of locking and unlocking and when locked are capableof drawing said needle back into the syringe barrel assembly.
 14. Thedisposable safety syringe assembly of claim 10 or 11, in which thesyringe assembly is sealed in a sterile manner.
 15. The disposablesafety syringe assembly of claim 10 or 11, wherein the needle assemblyhas been pushed through the forward end of the barrel assembly, andlocked therein by the friction between the two constricted tip portions,forming an interference or wedge fit.
 16. The disposable safety syringeassembly of claim 10 or 11, wherein the barrel assembly includes afinger extension extending radially outward, said finger extension beingpositioned closer to said rearward end than to said forward end thereof.17. The disposable safety syringe assembly of claim 10 or 11, whereinthe plunger assembly includes a break-off means, located closer to saidforward end than to said rearward end thereof, such that afterwithdrawal of the needle assembly into said barrel assembly, saidplunger assembly may be broken off, rendering the syringe incapable ofreuse.